Use single `languages::{rust_lang, markdown_lang}` in tests across the codebase (#44282)

This allows referencing proper queries and keeping the tests up-to-date.

Release Notes:

- N/A
16666f5357Kirill Bulatov committed on 12/6/2025, 6:49:21 PM· committed by GitHubparentb2e35b5
22 files changedLine totals unavailable